(1) Field of the Invention
The present invention relates to an electrically driven oil pump utilized as an oil pump and particularly relates to an electrically driven dual pump in which pump mechanisms of two different systems are equipped.
(2) Description of Related Art
In a hybrid (automotive) vehicle in which an internal combustion engine is stopped under a particular vehicle driving condition which is one of vehicular drive sources, for a hydraulic pressure supply to a transmission during a stop of the engine, it is general practice that the electrically driven oil pump is used. In a case where two hydraulic pressure systems for each of which a requested hydraulic pressure or an oil quantity is different are present, it is desirable to provide a dual pump in which two pump mechanisms of the two systems are equipped.
Each of a Japanese Patent Application First Publication (tokuhyou) No. 2006-517634 published on Jul. 27, 2006 and a Japanese Utility Model Registration Application Publication No. Showa 57-083290 published on May 22, 1982 exemplifies a previously proposed composite oil pump.
In the previously proposed composite oil pump, a plurality of pump mechanisms are arranged in parallel to each other within a housing and a single drive shaft drives these pump mechanisms at the same time. In this case, the individual pump mechanisms are constituted by vane pumps, a rotor of each of the pump mechanisms is attached onto a common drive shaft.
In addition, a Japanese Patent Application First Publication No. 2012-067735 published on Apr. 5, 2012 exemplifies another previously proposed electrically driven oil pump. In this other previously proposed electrically driven oil pump, a housing in which coils are equipped and an outer rotor having permanent magnets constitute a kind of an electrically driven motor and an inner rotor is rotated together with the outer rotor to obtain a pump action.